Variable volume vane type pump



y 1966 c. H. WHITMORE ETAL 3,252,423

VARIABLE VOLUME VANE TYPE PUMP 3 Sheets-Sheet 1 Filed Jan. 10, 1964 22mmyum mm y 1966 c. H. WHITMORE ETAL 3,252,423

VARIABLE VOLUME VANE TYPE PUMP 3 Sheets-Sheet 2 Filed Jan. 10, 1964 y1955 c. H. WHITMORE ETAL 3,252,423

VARIABLE VOLUME VANE TYPE PUMP Filed Jan. 10, 1964 3 Sheet s:Sheet 5aonomsmi'amasok R United States Patent 3,252,423 VARIABLE VOLUME VANETYPE PUMP Charles H. Whitmore, Savage, Russell G. Winquist, St.

Paul, and Sheldon E. Thorson, St. Louis Park, Minn,

assignors to Continental Machines, Inc., Savage, Minn,

a corporation of Minnesota Filed Jan. 10, 1964, Ser. No. 337,043 9Claims. (Cl. 103120) This invention relates to pumps and refers moreparticularly to variable volume vane type pumps.

Pumps of this type have a rotor which revolves on a fixed axis, and aring which encircles the rotor and shifts radially towards and fromconcentricity with. the rotor, to vary the volume of fluid delivered bythe pump. The closer the ring is to being concentric with the rotor, theless fluid the pump delivers; but the pressure developed by the pumpremains substantially constant throughout the full volume range.

As is conventional in pumps of this type, the rotor hascircumferentially spaced slots extending inwardly from its periphery inwhich vanes are slidably received to be carried around circular orbitsby the revolving rotor with their outer end portions projecting beyondthe periphery of the rotor and spanning the distance between the rotorand the ring. The vanes thus cooperate with the rotor, the ring, and endwalls in the pump body between which the rotor, ring and vanes areconfined, to

define pumping chambers which increase and decrease in size as the rotorrevolves, because of eccentricity between the ring and the rotor; andsince these chambers are in communication with an inlet port as they areincreasing in size and communicate with a discharge port as theydecrease in size, the rotating vanes produce suction at the inlet portto draw fluid into the pump and pressure at the discharge port.

For more than half the circular orbit of the vanes which encompassestheir travel through the pressure zone, the fluid pressure in the pumppresses the vanes against the inside surface of the ring as they slidetherealong; but the force with which the vanes are pressed against thering is not uniform, being greatest as the vanes enter and as they leavethe pressure zone. This difference in pressure exerted upon the ring bythe vanes and the fact that the areas of the ring surface subjected tothe greatest pressure were always the same, caused a very markedunevenness in wear on the ring in pumps of this type heretoforeavailable. Long before any other portion of the pump began to show anysigns of significant wear, the inside surface of the ring was hopelesslyworn. While the ring could be replaced, to do so often was extremelyexpensive due to the need for shutting down the equipment with which thepump was used. In any event,'the need for frequent replacement of thering was an irksome inconvenience.

In recognition of this objection to variable volume vane type pumpsheretofore available, the present invention has as its purpose andobject to provide a pump of the character described wherein the wear onthe volume adjusting ring against which the vanes bear will be uniformlydistributed around the entire circumference of the ring, which of coursegreatly increases its useful life.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accompanying drawings illustrate one complete ice example of thephysical embodiment of the invention,

constructed according to the best mode so fardevised for the practicalapplication of the principles thereof, and in which:

FIGURE 1 is a cross sectional view through a pump embodying thisinvention;

FIGURE '2 is a sectional view through FIGURE 1 on the plane of the line22; and

FIGURE 3 is a greatly enlarged view of a portion of the pump rotor andthe ring which encircles it, to illustrate how the forces that act uponthe ring are utilized in this invention to solve the problem to whichthe invention is directed.

Referring now particularly to the accompanying drawings, the numeral 5designates the body of the pump and which, as best seen in FIGURE 2,comprises a base section 6, a rotor housing 7 and a cover 8. These threeparts are bolted together with the rotor 9 of the pump in positioninside its housing 7 and mounted on the pump shaft 1b which isjournalled in bearings 11 and 12, respectively located in the basesection 6 and in the cover 8.

The rotor 9 has a plurality of substantially radially disposed slots 13extending in from its periphery and opening to the opposite ends orfaces of the rotor, which are flat. Slidably received in these slots arevanes 14, the vanes being freely movable radially with respect to therotor, to permit their outer end portions to project beyond theperiphery of the rotor to span the space between the rotor and theinside surface 15 of a pressure ring 16 which encircles the rotor. Thusthe ring 16, the rotor, the vanes and end walls-provided by a port disc17 and a thrust plate or disc 18 between which the assembled rotor,vanes and pressure ring are confinedcoact to define fluid pumpingchambers 19 which travel in circular orbits as the rotor revolves.

The pressure ring 16 is normally eccentric to the axis of the rotor and,hence, the pumping chambers 19 increase in size. during one-half oftheir orbital rotation about the rotor axis, and decrease in size duringthe other of rotation. As the pumping chambers 19 increase in size orvolume, they sweep past and communicate with an arcuate inlet port 20 inthe port disc 17 to receive fluid therefrom, and as they decrease insize they sweep past and communicate with an arcuate discharge port 21in the port disc and, in so doing, force the fluid into this port fordelivery out of the pump. There is, therefore, a suction zone at oneside of the rotor axis and a pressure zone at the opposite side thereof.

An inlet 22 in the base section 6 communicates with the inlet port 20,and an outlet 23, also in the base section 6, communicates with thedischarge port 21.

A governor spring 25 which reacts between the pressure ring 16 and thepump body, yieldingly urges the ring to its position of maximumeccentricity with respect to the rotor, which position may be defined byan adjustable stop 26 located diametrically opposite the spring 25.

The governor spring 25 is preferably located in a pocket 27 thatprojects radially from the main cavity or bore 28 of the rotor housing,and applies its force upon the pressure ring through a shoe 29 which hasan arcuate surface corresponding to and fitting the outer cylindricalsurface of the ring. Attention is directed to the fact that theengagement of the shoe 29 with the ring is symmetrical with respect tothe axis along which the spring exerts its thrust upon the ring and thatthis axis is radial to the rotor.

The magnitude of the bias exerted upon the pressure ring by the governorspring 25 is adjustable by means of a screw 30, and by its adjustmentthe pressure developed and delivered by the pump may be set.

As the work being performed by the hydraulic system supplied by the pumpvaries, the volume of fluid delivered must accordingly vary, and thisresult is accomplished by the translatory shifting of the pressure ringtowards and from its position of maximum eccentricity with respect tothe rotor. It should be noted that in shifting from one position toanother, the pressure ring moves along a path which coincideswith theaxis of thrust of the governor spring and that, in all positions of thering, its axis lies in a plane which is common to the rotor axis, andin'FIGURE 3 is identified by the line 31. It should also be noted thatthe in let port and hence the suction side of the pump, lies at one sideof the plane identified by the line 31 (below the plane in the drawings)and that the discharge port 21 and the pressure zone of the pump, whenin operation, is at the other side of this plane (above the plane in thedrawings).

Inside the ring the hydraulic force is nearly constant throughout thefull range of volume of fluid delivered by the pump. However, thedirection of this force changes as the volume of delivered fluid varies,to the end that the horizontal component of this hydraulic force, i.e.along the plane of line 31, opposing the governor spring 25, is at alltimes substantially equal to the force of the spring. To illustrate atfull volume output, the spring force may be 450 lbs. balanced by a 450lb. horizontal component of the hydraulic force, while at no volume thespring force might be 750 lbs. balanced by a 750 lb. horizontalcomponent of the hydraulic force. Those skilled in the art will, ofcourse, appreciate that during the no volume" condition of operation,inevitable slippage, i.e. fluid that passes from the pressure zoneacross the vanes to the suction zone, and leakage-ordinarily termed casedrain-keeps the pressure ring from moving into exact concentricity withthe rotor. In other words, even when the pump is not delivering fluid,the ring 16 is still not absolutely concentric with the rotor.

Since the suction and pressure zones which obtain when the pump is inoperation lie at opposite sides of the plane defined by the horizontalline 31 in FIGURE 3, with the pressure zone being thereabove, the fluidpressure inside the ring 16 also tends to push the ring to one side ofthis horizontal planeupwardly in the drawings-with a force thatincreases as the ring moves towards concentricity and decreases as thering moves in the opposite direction.

Obviously, of course, this upward thrust upon the pressure ring tendingto move it to one side of the plane 31, must be opposed, for otherwisethe ring would not be confined to its desired translating movement alongthe plane 31. Heretofore, this was done by having the outer periphery ofthe ring bear against a shoe so mounted in the body of the pump that itdid not in anywise interfere with free forth and back movement of thering as the direction of the hydraulic force within the ring changed andthe governor spring yielded or expanded to balance the fluid pressureopposing the spring. The Miller et al. Patent No. 2,764,941, illustratesthis floating shoe support. It is significant that although thisfloating shoe support did not interfere with free forth and backmovement of the ring, it did hold the ring against rotation.

As noted hereinbefore, for part of the orbit of the vanes, fluidpressure in the slots 13 under the inner ends of the vanes, forces themagainst the inside surface 15 of the ring 16. This occurs when the slots13 are in communication with an arcuate outlet port 34 which opens tothe pump outlet and through which the fluid in the slots is expelled;and arcuate inlet port 33 provides for the admission of fluid into theinner ends of the slots.

Since the arcuate outlet port 34 encompasses a greater angle of rotorrotation than the discharge port 21 and is substantially symmetricalwith it, the inner ends of the slots are in Communication with the port34 after the vanes leave the port 21. Accordingly, along that segment ofthe orbit of the vanes, identified in FIGURE 1 by the angle 35, thevanes have full pressure under them and little or no pressure on top ofthem. The same is true for that part of the segment of the orbitidentified by the angle 35:: when the vanes are approaching the suctionzone and after the pressure behind the vanes loses its effect upon thesloping outer edge of the vanes. The portions of the ring surface 15traversed during these two portions of orbital vane travel, thus aresubjected to the greatest vane pressure, and hence take far more wearthan the rest of the ring surface 15.

It is this condition which was primarily responsible for the uneven wearon the inside surface of the pressure ring in pumps of this typeheretofore available; but since the design requirements of pumps of thistype preclude eliminating this increased outward pressure on the vanesas they approach the high and low pressure zones, and in any event pressagainst the ring harder as they travel through the pressure zone thanthey do in the suction zone, the objectionable condition was reluctantlyaccepted as an inevitable consequence of a pump of this nature.

This invention does not eliminate the difference in pressure which thevanes exert upon the inside surface of the pressure ring as they travelaround their orbit, but it does distribute the wear resulting therefromsubstantially uniformly around the entire circumference of the ring byrotating the ring very slowly around the rotor.

Through the discovery of this invention, it is now known that if thefreely shiftable thrust receiving shoe used in the past to hold thepressure ring against being shove-d out of a position at which itscenter is on the plane defined by the line 31, is replaced by astationary abutment 40 having a fiat surface parallel to the plane offorth and back movement of the pressure ring, the ring will creep aroundthe rotor and gradually present its entire inside surface to the zonesof maximum pressure between the vanes and the ring.

The abutment means 40 is conveniently provided by the flat end of ascrew 41 threaded into the rotor housing 7 with its axis normal to theplane 31. In this manner, the exact location of the flat surface whichprovides the abutment means, with respect to the center of the rotor andthe ring, may be accurately adjusted. Since the pressure ring neveroccupies a position fully concentric with the rotor, it is preferablefor the axis of the screw 41 to be slightly to that side of the rotorcenter opposite that at which the governor spring exerts its force.

By virtue of the thrust of the pressure ring against the fiat abutmentsurface 40 and the fact that the engagement therebetween is as far toone side of the plane 31 as the diameter of the pressure ring willallow, it follows that with each translating motion of the pressure ringto adjust the volume of fluid delivered by the pump, the pressure ringwill roll upon the abutment surface 40 despite any friction, representedby the arows 38, which may exist between the pressure shoe 29 and thering; and to minimize this friction, the surface of the shoe 29 whichbears against the pressure ring, has a covering or lining 29' of Teflon,or is otherwise rendered as frictionless as possible.

Although the pressure ring 16 rolls in one direction across thestationary surface 40 as the ring moves towards concentricity with therotor, and in the opposite direction when the ring moves away fromconcentricity, it has been found that the angle through which the ringturns in one direction is always slightly greater than in the other. Whythis is so is not entirely clear, but apparently it has something to dowith the fact that the hydraulic pressure pressing the ring against theabutment 40 is increasing as the ring moves towards concentricity anddecreasing as it moves in the oppoiste direction. Be-

cause of this, the diameter of the ring may be infinitesi- 1 5 mallygreater while it is moving in one direction than it is when moving inthe opposite direction; especially when the work being performed by thehydraulic system supplied by the pump requires a rapid change from asmall volume to a larger volume and a slow change from greater volume tolesser volume.

Possibly also, there may be some very slight deformation of the surfaceof the ring or of the abutment 40, as the ring rolls back and forth,which conceivably could produce slippage between the contactingsurfaces, greater in one direction than the other. But whatever theexplanation may be, it is definitely known that with each cycle of forthand back motion of the pressure ring, the ring is given a tiny incrementof rotation in one direction, so

' that the ring creeps very slowly around the rotor.

From measurements that have been made, it has been determined thatseveral thousand movements of the ring are required to rotate the sameone-eighth of an inch. Nevertheless, this very slow creeping of the ringaround the rotor gradually and continually presents another portion orarea of the inside surface of the ring to the most serious wearresulting from the friction between the vanes and the ring as they ridearound the inside surface of the ring; so that instead ofhavingrelatively short segments of the inside surface of the ring carry all ofthis most serious wear-producing force, the wear is distributeduniformly around the entire circumference of the ring. The net result isthat the pressure ring will last practically as long as any otherportion of the pump subject to wear.

From the foregoing description taken in connection with the accompanyingdrawings, it will be apparent that this invention constitutes asubstantial improvement in vane-type variable volume pumps.

What is claimed as our invention is:

1. In a variable volume pump of the vane type, having a body, a rotorinside the body constrained to rotate about a fixed axis and having aplurality of slots opening to its' periphery and spaced around itscircumference, a ring encircling the rotor and having an inside surface,vanes in said slots to be carried around orbits by the revolving rotorwith their outer end portions projecting beyond the periphery of therotor and spanning the distance between the rotor and the ring, andwhich are pressed against the inside surface of the ring by the fluidpressure developed .in the pump with a force that varies as the vanestravel decrease in size as the rotor revolves inside the ring as long asthe ring is eccentric to the rotor, and biasing means acting upon thering to yieldingly urge the same along said path toward a position ofmaximum eccentricity with respect to the rotor in opposition to fluidpressure developed in the pump so that the ring moves forth and backalong said path as the volume of fluid delivered by the pump varies,

the improvement whereby wear on the inside surface of the ring caused bythe sliding engagement under pressure between the vanes and said surfaceof the ring is distributed substantially uniformly around the entirecircumference of the ring, and which improvement comprises:

means acting upon the ring and responsive to forth and back movement ofthe ring to effect rotation of the ring in one direction in tinyincrements, so that the ring creeps aroundthe rotor as the pump operatesto gradually and continually present a different portion of the insidesurface of the ring to the most serious wear-producing pressure of thevanes upon the ring.

6 2. In a variable volume pump of the vane type, having a body, a rotorinside the body constrained to rotate about a fixed axis and having aplurality of slots opening to its periphery and spaced around itscircumference, a ring encircling the rotor and having an inside surface,vanes in said slots to be carried around orbits by the revolving rotorwith their outer end portions projecting beyond the periphery of therotor and spanning the distance between the rotor and the ring, andwhich are pressed against the inside surface of the ring by the fluidpressure developed in the pump with a force that varies as the vanestravel around their orbits, end walls on the body between which therotor, its vanes, and the ring are confined, means mounting the ring fortranslatory forth and back shifting in the body along a defined path inall portions of which the ring axis lies in a plane common to the rotoraxis so that the rotor, the ring, the vanes and the end walls cooperateto form pumping chambers which increase and decrease in size as therotor revolves inside the ring as long as the ring is eccentric to therotor, and biasing means acting upon the ring to yieldingly urge thesame along said pat-h toward a position of maximum eccentricity withrespect to the rotor in opposition to fluid pressure developed in thepump so that the ring moves forth and back along said path as the volumeof fluid delivered by the pump varies,

the improvement whereby wear on the inside surface of the ring caused bythe sliding engagement under pressure between the vanes and said surfaceof the ring is distributed substantially uniformly around the entirecircumference of the ring, and which improve- .ment comprises:

abutment means fixed with respect to the body and :bearing against aportion of the ring which is spaced to one side of said plane, theengagement of said aibutment means with the ring cooperating with theeffect of the varying forces acting upon the ring during operation ofthe pump to cause the ring to turn slightly, first in one direction andthen slightly farther in the other direction as the ring shifts forthand back, so that the ring creeps around the rotor as the pump operatesand gradually and continually presents different portions of its insidesurface to the most serious wear-producing pressure of the vanes uponit.

3. In a variable volume pump as set forth in claim 2, wherein the fluidpressure developed in the pump and reacting between the rotor and thering also imparts an outward thrust upon the ring in the directiontending to move it to one side of said plane, and wherein said abutmentmeans is at the same side of said plane and has a surface which bearsagainst the outer periphery of the ring so that the ring rolls on saidsurface as the ring shifts forth and back.

4. In a variable volume pump, the structure set forth in claim 3,further characterized by: a shoe interposed between the biasing meansand the periphery of the ring; and anti-friction means between the shoeand the ring.

5. In a variable volume pump, the structure set forth in claim 3,further characterized by the fact that said surface of the abutmentmeans is flat and parallel with said plane.

6. In a variable volume pump, the structure set forth in claim 3,further characterized by the fact that said abutment means is a screwthreaded into a portion of the body with the inner end of the screwfacing the periphery of the ring and so positioned by adjustment of thescrew as to have the periphery of the ring bear thereon when the centerof the ring lies substantially on said plane.

7. The variable volume pump of claim 6, wherein the inner end of thescrew is fiat and parallel with said plane. v

8. The variable volume pump of claim 7, wherein the axis of the screw isoff-center with respect to the axis of the rotor and lies at the side ofthe rotor axis opposite that at which the biasing means is located.

9. In a variable volume pump of the vane type, having a body, a rotorinside the body constrained to rotate about a fixed axis and having aplurality of slots opening to its periphery and spaced around itscircumference, a ring enclircling the rotor and having an insidesurface, vanes in said slots to be carried around orbits by therevolving rotor with their outer end portions projecting beyond theperiphery of the rotor and spanning the distance between the rotor andthe ring, and which are pressed against the inside surface of the ringby the fluid pressure developed in the pump with a force that varies asthe vanes travel around their orbits, end walls on the body betweenwhich the rotor, its vanes, and the ring are confined, means mountingthe ring for translatory forth and back shifting in the body along adefined path in all portions of which the ring axis lies in a planecommon to the rotor axis so that the rotor, the ring, the vanes and theend walls cooperate to form pumping chambers which increase and decreasein size as the rotor revolves inside the ring as long as the ring iseccentric to the rotor, and a spring reacting between the body and thering to yieldingly urge the ring along said path toward a position ofmaximum eccentricity with respect to the rotor in opposition to fluidpressure developed in the pump so that the ring moves forth and backalong said path as the volume of fluid delivered by the pump varies, thefluid pressure in the pump biasing the ring to one side of said plane,

the improvement whereby wear on the inside surface of the ring caused bythe sliding engagement under pressure between the vanes and said surfaceof the ring is distributed substantially uniformly around the entirecircumference of the ring, and which im provement comprises:

a screw threaded into the body at the side thereof towards which thefluid pressure in the pump biases the ring, with its axis perpendicularto said plane and its end bearing against the periphery of the ring, tosupport the same against the thrust imposed upon the ring by the fluidpressure in the pump, the end of the screw being flat and parrallel tosaid plane so that the ring rolls thereon as it shifts forth and back; ashoe interposed between said spring and the periphery of the ring; and

anti-friction means on the shoe and through which the thrust of thespring is applied to the ring, fiat and parallel to said plane so thatthe ring so that the force of the spring is applied to the ring withoutsignificantly resisting rotation of the ring as it rolls upon the end ofthe screw.

References Cited by the Examiner UNITED STATES PATENTS 2,035,465 3/1936Erskine et al 103-120 2,592,247 4/1952 Coe 103-120 2,600,633 6/1952French 103-120 2,764,941 10/1956 Miller et al. 103-120 2,955,542 10/1960Gaubatz 103-120 3,052,189 9/1962 Head 103-120 3,091,185 5/1963 Eames103-136 3,107,628 10/1963 Rynders et al 103-120 MARK NEWMAN, PrimaryExaminer.

W. I. GOODLIN, Assistant Examiner.

1. IN A VARIABLE VOLUME PUMP OF THE VANE TYPE, HAVING A BODY, A ROTORINSIDE THE BODY CONSTRAINED TO ROTATE ABOUT A FIXED AXIS AND HAVING APLURALITY OF SLOTS OPENING TO ITS PERIPHERY AND SPACED AROUND ITSCIRCUMFERENCE, A RING ENCIRCLING THE ROTOR AND HAVING AN INSIDE SURFACE,VANES IN SAID SLOTS TO BE CARRIED AROUND ORBITS BY THE REVOLVING ROTORWITH THEIR OUTER END PORTIONS PROJECTING BEYOND THE PERIPHERY OF THEROTOR AND SPANNING THE DISTANCE BETWEEN THE ROTOR AND THE RING, ANDWHICH ARE PRESSED AGAINST THE INSIDE SURFACE OF THE RING BY THE FLUIDPRESSURE DEVELOPED IN THE PUMP WITH A FORCE THAT VARIES AS THE VANESTRAVEL AROUND THEIR ORBITS, END WALLS ON THE BODY BETWEEN WHICH THEROTOR, ITS VANES, AND THE RING ARE CONFINED, MEANS MOUNTING THE RING FORTRANSLATORY FORTH AND BACK SHIFTING IN THE BODY ALONG A DEFINED PATH INALL PORTIONS OF WHICH THE RING AXIS LIES IN A PLANE COMMON TO THE ROTORAXIS SO THAT THE ROTOR, THE RING VANES AND THE END WALLS COOPERATE TOFORM PUMPING CHAMBERS WHICH INCREASE AND DECREASE IN SIZE AS THE ROTORREVOLVES INSIDE THE RING AS LONG AS THE RING IS ECCENTRIC TO THE ROTOR,AND BIASING MEANS ACTING UPON THE RING TO YEILDINGLY URGE THE SAME ALONGSAID PATH TOWARD A POSITION OF MAXIMUM ECCENTRICITY WITH RESPECT TO THEMOTOR IN OPPOSITION TO FLUID PRESSURE DEVELOPED IN THE PUMP SO THAT THERING MOVES FORTH AND BACK ALONG SAID PATH AS THE VOLUME OF FLUIDDELIVERED BY THE PUMP VARIES, THE IMPROVEMENT WHEREBY WEAR ON THE INSIDESURFACE OF THE RING CAUSED BY THE SLIDING ENGAGEMENT UNDER PRESSUREBETWEEN THE VANES AND SAID SURFACE OF THE RING IS DISTRIBUTEDSUBSTANTIALLY UNIFORMLY AROUND THE ENTIRE CIRCUMFERENCE OF THE RING, ANDWHICH IMPROVEMENT COMPRISES: